Process for preparing a segmented linear polyurethane polymer

ABSTRACT

AN IMPROVED PROCESS FOR PREAPRING A SEGMENTED LINEAR POLYURETHANE POLYMER IS PROVIDED WHICH CONSISTS OF PREPARING A PREPOLYMER BY REACTINF POLYTETRAMETHYLENE ETHER GLYCOL WITH METHYLENEBIS(4-PHENYL-ISOCYANATE) AND CHAIN EXTENDING THE RESULTING ISOCYANATE TERMINATED PREPOLYMER IN SOLUTION, WITH A SUITABLE ALIPHATIC DIAMINE OR A GLYCOL, THE IMPROVEMENT WHICH COMPRISES EMPLOYING A POLYTETRAMETHYLENE ETHER GLYCOL HAVING A MOLECULAR WEIGHT BETWEEN 2500 AND 7500. IN ADDITION, THE INVENTION ALSO PROVIDES AN IMPROVED SPANDEX FIBER PREPARED FROM SUCH SEGMENTED LINEAR POLYURETHANE POLYMER.

April 9 KOROSCIL 3,80%,812

PROCESS FOR PREPARING A SEGMENTEI) LINEAR POLYURETHANE POLYMER Filed Nov. 3, 1972 2 Sheets-Sheet 1 MODUL us, g/d

A B! A EXTE/VS/O/V,

EEG

April 16, 1974 A. KOROSCIL 3,8@4,8l2

PROCESS FOR PREPARING A SEGMEN TED LINEAR POLYURETHANE POLYMER Filed Nov. 3, 1972 2 Sheets-Sheet 2 MODULUS, 9/0

IOO

EXTE/VS/O/V,

United States Patent Office Patented Apr. 16, 1974 U.S. Cl. 260-775 AM Claims ABSTRACT OF THE DISCLOSURE An improved process for preparing a segmented linear polyurethanepolymer is provided which consists of preparing a prepolymer by reacting polytetramethylene ether glycol with methylenebis(4-phenyl-isocyanate) and chain extending the resulting isocyanate terminated prepolymer, in solution, with a suitable aliphatic diamine or a glycol, the improvement which comprises employing a polytetramethylene ether glycol having a molecular weight between 2500 and 7500. In addition, the invention also provides an improved spandex fiber prepared from such segmented linear polyurethane polymer.

Generally stated, the subject matter of the present invention relates to an improved method for preparing segmented polyurethane polymers. More particularly, the invention relates to an improved method for preparing segmented polyurethane polymers from high molecular weight polytetramethylene ether glycol, and to the elastomeric fibers spun therefrom.

BACKGROUND OF THE INVENTION Spandex fibers and films are composed of segmented linear polyurethane polymers in which the polymer molecules contain both hard and soft segments. The soft segments are the residues of hydroxyl-terminated polyesters or polyethers of high molecular weight. The hard segments contain urethane and urea groups which result from the reaction of these polyesters or polyethers with organic diisocyanates, and the resultant isocyanate-terminated prepolymers are further polymerized or chainextended by reacting them with difunctional compounds such as diamines or glycols.

In the manufacture of stretch garments from such fibers it is necessary for such garments to be capable of being stretched without a great exertion of force, and also that such garments will comfortably fit many sizes of wearers. The fibers should have a relatively flat recovery modulus curve after repeated stretch and relaxation cycles, that is fibers with a relatively constant holding, or support power as the fibers are stretched and relaxed Although the art has developed to the extent that stretch garments are commonly accepted and worn, the development of fibers with a relatively flat recovery modulus curve has eluded all attempts at development.

The present invention represents the culmination of a long series of investigations conducted largely by the inventor directed to uncovering a method for preparing a segmented linear polyurethane polymer which is capable of being prepared into a spandex fiber having a relatively fiat recovery modulus curve.

Accordingly, it is a primary object of the present invention to provide a method for preparing segmented linear polyurethane polymers which are capable of being prepared into spandex fibers and films that have a relatively fiat recovery modulus curve.

Another object of the invention is to provide fibers with a high ultimate elasticity, that is a high break elongation.

It is yet another object of the invention to provide a non-gelling fiber spinning solution of segmented linear polyurethane polymers.

Generally then, it is an object of the invention to provide spandex fibers which have a relatively flat recovery modulus curve, as well as fibers which have the normal desirable physical properties of spandex fibers.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be realized by practice of the invention, the objects and advantages being realized and attained by means of the methods, processes, instrumentalities and combinations particularly pointed out in the appended claims.

THE INVENTION To achieve the foregoing objects and in accordance with its purpose as embodied and broadly described, the present invention relates to an improved process for perparing a segmented linear polyurethane polymer which consists of preparing a prepolymer by reacting polytetramethylene ether glycol with methy1enebis(4-phenyl isocyanate) and chain extending the resulting isocyanate terminated prepolymer, in solution, with a suitable aliphatic diamine or a glycol, the improvement which comprises employing a polytetramethylene ether glycol having a molecular weight between 25 00 and 7500.

The present invention further provides an improved spandex fiber having a relatively flat recovery modulus curve.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

The utilization of polytetramethylene ether glycol as the soft segment of the polyurethane polymer is well recognized and accepted in the art. U.S. Pat. No. 2,929,- 800, Hill, discloses the use of polyalkylene ether glycols, including polytetramethylene ether glycol, having a molecular weight of -0 to 10,000, in conventional types of elastomeric polyurethane polymers. In addition, U.S. Pat. No. 3,071,557, Frazer et 211., discloses the use of tolylene diisocyanate modified polytetramethylene ether glycol, having a molecular weight of up to 8000, in a conventional polyurethane polymer. The present invention particularly resides in the discovery that the molecular weight of the polytetramethylene ether glycol is of particular significance to the recovery modulus curve of fibers spun from polymers prepared therefrom.

The polytetramethylene ether glycol of use in this invention then, should have a molecular weight between 2500 and 7000, preferably between 3200 and 5000. The high molecular weight glycol can be obtained by ring polymerization of tetrahydrofuran or by reacting 2 moles of polytetramethylene ether glycol of low molecular weight with 1 mole of a diisocyanate, such as tolylene diisocyanate or hexamethylene diisocyanate. The latter procedure effectively doubles the molecular weight of the polytetramethylene ether glycol.

The isocyanate-terminated prepolymer is produced by reacting 1 mole of the polytetramethylene ether glycol of high molecular weight with between 1.5 moles, preferably between 1.7 moles and 2.2 moles, of methylenebis(4- phenyl isocyanate). The reaction is carried out at a temperature between 20 and 150 C., preferably between 60 and C.

Chain extention of the isocyanate-terminated prepolymer is carried out by reacting the prepolymer in solution with a suitable aliphatic diamine or a glycol. The equivalent amount of isocyanate-terminated prepolymer and diamine or glycol are employed. The chain-extension reaction can be carried out in a conventional manner at a temperature between 0 and 0., preferably between 20 and 40 C.

3 4 Solvents of use in the chain extension process are conylformamide is added to reduce the solids concentration ventional solvents for polyurethane polymers and have to 30 percent. Similarly, when the viscosity reaches 1400 the same meaning as the term polyacrylonitrile solvents poises at 30 percent solids, the solution is further diluted in U.S. Pat. No. 3,388,100, Thoma et al. The preferred with dimethylformamide to 25 percent solids, and when solvents of this class are the dimethylcarbamyl comthe viscosity reaches 450 poises, the solution is diluted pounds such as dimethylformamide, dimethylacetamide, with dimethylformamide to 17 percent solids. After 1 dimethylpropionamide, the corresponding alkoxymethyl hour, the solution is treated with 5 g. of n-butylamine. A compounds such as methoxydimethylacetamide, and other portion of the solution, 2500 g. is treated with 70 g. of a highly polar solvents such as N-methylpyrrolidone and 50/50 titanium dioxide-dimethylformamide mixture and dimethyl sulfoxide. 1Q ml. of a 33 percent 4,4'-butylidenebis(6-tert-butyl-rn- Suitable organic chain extending agents include, for excresol) solution in dimethylformamide. ample, ethylenediamine, hydrazine, dimethylpiperazine, The polymer solution is forced at constant speed by methyliminobispropylamine, m-phenylenediamine, 4,4-dimeans of a precision gear pump through a spinnerette aminodiphenylmethane, ethylene glycol, hexamethylene immersion in water, the spinnerette having 70 holes of glycol, diethylene glycol, hydroquinone, etc. The pre- 15 0.006 dia. The extruded, semi-plastic monofilaments are ferred aliphatic diamine chain extending agent is a combrought together to form a single coalesced multifilament bination of ethylenediamine and methyliminobispropylfiber which is passed through a series of baths to extract amine. The concentration of ethylenediamine to methylthe dimethylformamide by countercurrent washing with iminobispropylamine is in a mole ratio of 10:1. water. The wet fiber is then continuously dried and cured In a variation of the process of this invention, a glycol 90 on a belt dryer and finally wound on spools. containing urea moieties, and formed by reaction of 1 Fibers of 475 denier have a 300 percent modulus of mole of an organic diisocyanate with 2 moles of an amino about 0.062 g./d., an ultimate tenacity of about 0.626 alcohol, is the preferred glycol chain extending agent. g./d. and an ultimate elongation of about 750 percent. Such glycols have been referred to as adducts. Suitable The holding or support power of the fibers of this examino alcohols have alkylene chains of 2-6 carbon atoms, ample is measured by a procedure based on methods deas exemplified by Z-aminoethanol, 4-amino-1-butanol, etc. scribed in Industrie Textiles Belge 7, 69-77 (1965) and The diisocyanate is preferably methylenebis(4-1phenyl iso- Du Pont Technical Information Bulletin L-17 (1965). cyanate), but other diisocyanates, such as tolylene diiso- An Instron tensile testing machine, is used for the stresscyanate, may be used. The glycol can be reacted with strain tests using three cycles of loading and unloading an isocyanate-terminated prepoly-mer in a conventional and maxi-mum elongations of 200 and 300 percent. The manner or it can be reacted in situ with the components holding power is calculated for different extensions from of the prepolymer, namely; polytetramethylene ether glyto 275 percent using the formula: col and methylenebis(4-phenyl isocyanate).

The polymer solution can be wet or dry spun by con- Holding power: m gram; recovery cycle ventional techniques to give an elastomeric filament hav- 35 emer ing the desired elastic recovery properties, or the solu- Instead of holding power, the equivalent expression tion can be used to form other shaped articles, such as modulus ete tion h s been used.

The modulus retention of the fibers at 200 and 300 films or castings.

Dyes, pigments, antioxidants, stabilizers and other adpercent cycling, expressed as the third cycle recovery ditives may be incorporated in the polyurethane solution modulus X 0- at elongations from 35 to 275 perby adding at any stage before formation of the shaped Cent are Sh wn in Table 1 and graphically in FIG. 1.

article, but are preferably added to the polymer solution Curves A and A of FIG. 1 correspond to maximum elonaftcr the chain extension step. gations of 200 and 300 percent respectively.

TABLE 1 Third cycle recovery modules (MX10- nt extension 200% cycling elongation 62 91 117 134 152 179 215 300% cycling elongation 39 61 86 101 108 110 116 128 144 172 227 The polymer solutions obtained by the process of this When, for comparison, a similar polymer solution is invention are non-gelling, have long storage lives and are 09 prepared using a non-extended polytetramethylene ether easily spun into filaments or cast into films. glycol of average molecular weight 2050 instead of the The following examples are provided for illustrative extended polytetramethylene other glycol, fibers of 413 purposes and may include particular features of the indenier spun from the solution have a 300 percent modulus vention. However, the examples should not be construed of about 0.211 g./d., an ultimate tenacity of about 1.028 as limiting the invention, many variations of which are 99 g./d. and an ultimate elongation of about 581 percent.

possible without departing from the spirit or scope The holding power of the fibers is shown in Table 2 thereof. and graphically in 'FIG. 1. Curves B and B of FIG. 1

Example I correspond to a maximum elongation of 200 and 300 per- To an adduct formed in situ by mixing 103.1 g. of 2- cent respectively aminoethanol, 11,000 g. of dimethylformamide and 211.3 09 Third cycle recovery modulus (M 10 at extension:

TABLE 2 200% cycling elongation 87 121 161 179 201 244 337 300% cycling elongation 41 79 120 136 144 153 171 201 246 327 405 g. of methylenebis(4-phenyl isocyanate) there is added Curve A of FIG. 1 should be compared with Curve B,

4830 g. of an extended polytetramethylene ether glycol of and Curve A with Curve B. It will be noted that Curves average molecular weight 4200, formed by reaction of 2 70 A and A are flatter than Curves B and B, respectively. moles of polytetramethylene ether glycol of average mo- The average increase in modulus in the fiatest section, lecular weight of 1970 with 1 mole of tolylene diisobetween 50 and 200 percent extension, of the 300 percent cyanate (80/20 mixture of 2,4- and 2,6-isomers) at 90 curve of FIG. 1 for the product from the polyglycol of C. for 1 hour, and 534 g. of methylenebis(4-phenyl iso- 4200 molecular weight is 045x10" g./d./1 percent incyanate). The resulting solution is stirred at 80 C., and 75 crease in extension. The average increase in modulus bewhen the viscosity reaches 4000 poises, sufiicient dimethtween 50 and 200 percent extension for the product from 6 the polyglycol of 2050 molecular weight is 0.81X10- mer by reacting polytetramethylene ether glycol with g./d./1 percent of extension. methylenebis(4-phenyl-isocyanate) and chain extending This example demonstrates the relative constancy of the the resulting isocyanate terminated prepolymer in soluholding power of fibers prepared from a polytetramethtion with a suitable aliphatic diamine or a glycol, the

ylene ether glycol of 4200 molecular weight versus similar 5 improvement which comprises employing a polytetramethfibers prepared from. polytetramethylene ether glycol of ylene ether glycol having a molecular weight between 2050 molecular weight. 2500 and 7500.

Example II 2. The process according to clam 1 wherein the molecular weight of the polytetramethylene ether glycol is A mixture of 1000 g. of polytetramethylene ether glycol between 3200 and 5000.

(average molecular weight 4000) and 125 g. of methyl- 3. The process according to claim 1 wherein 1 mole of enebis(4-phenyl isocyanate) is heated at 75-80 C. for 1 the polytetramethylene ether glycol is reacted with behour. The resulting isocyanate-terminated prepolymer is tween 1.5 to 2.5 moles of methylenebis(4-phenyl isocyadiluted with 1125 g. of dimethylformamide. To a solution nate).

of 1.44 g. of methyliminobispropylamine in 1900 g. of 4. The process according to claim 3 wherein the condimethylformamide there is added g. of the prepolymer centration of methylenebis(4-phenyl isocyanate) is besolution, followed by 5.45 g. of ethylenediamine and 4.0 tween 1.7 to 2.2 moles.

ml. of a solution of diethanolamine in dimethylformamide 5. The process according to claim 1 wherein the reac- (1.l33 g./5 ml. solution). The prepolymer solution is tion between the polytetramethylene ether glycol and the slowly added until a viscosity of 120 poises is obtained. 20 methylenebis(4-phenyl isocyanate) is carried out at a tem- To the resulting polymer solution there is added 85 g. of perature of from about 20 to 150 C.

a 50/50 mixture of titanium dioxide and dimethylform- 6. The process according to claim 5 wherein the temamide and 7.8 ml. of a 33 percent solution of 4,4'-butyliperature is from about 60 to 90 C. denebis (fi-tert-butyl-m-cresol) in dimethylformamide. 7. The process according to claim 1 wherein the chain Fibers of 525 denier, spun by the process of Example extension reaction is carried out at a temperature of from I, have a 300% modulus of about 0.178 g./d., an ultimate about 0 to 100 C.

tenacity of about 1.064 g./d. and an ultimate elongation 8. The process according to claim 7 wherein the temof about 683 percent. The holding or support power of perature is from about 20 to 40 C. the fibers is shown in Table 3 and graphically in FIG. 2. 9. The process according to claim 1 wherein the pre- Curves A and -A' of FIG. 2 correspond to maximum elonpolymer is dissolved in a dimethylformamide. gations of 200 and 300 percent, respectively. 110. The process according to claim 1 wherein the isocyanate terminated prepolymer is reacted with an aliphatic Third cycle recovery modulus (MX10- at extension: diamine.

TABLE 3 200% cycling elongati0n....- 87 121 144 157 174 207 268 300% cycling elongation 49 85 112 117 121 128 143 175 228 322 When, for comparison, a similar polymer solution is 11. The process according to claim 10 wherein the prepared using a polytetramethylene ether glycol of averali hatic diamine is a mixture of ethylenediamine and age molecular weight 2000, instead of molecular weight methyliminobispropylamine.

4000, fibers of 334 denier spun from the solution have 12. The process according to claim 11 in which the a 300 percent modulus of about 0.257 g./d., an ultimate 4 concentration of ethylenediamine to methyliminobisprotenacity of about 0.993 g./d. and an ultimate elongation pylamine is in a mole ratio of 10:1.

of about 615 percent. 13. The process according to claim 1 wherein the iso- The holding power of the fibers is shown in T ble 4 cyanate terminated prepolymer is reacted with glycol. and graphi lly in Curves B and 015 FIG. 2 14. The process according to claim 13 wherein the correspond to maximum elongation of 200 and 300 per- 50 glycol contains urea moieties and is formed by the reaccent respectively.

tion of '1 mole of an organic diisocyanate with 2 moles Third cycle recovery modulus (MX 10*) at extension: of an amino alcohol.

TABLE 4 Curve A of FIG. 2 should be compared with Curve B, 15. A spandex fiber prepared from the segmented linear and Curve A with B. -It will be noted that Curves A and polyurethane polymer prepared according to claim 1. A are flatter than Curves B and B, respectively.

The average increase in modulus in the flatest section, References Cited between 50 and 200 percent extension, of the 300 percent 65 UNITED STATES PATENTS curve for the product from the polyglycol of 4000 mo ecular weight of 039x 10- g./d./1 percent increase in exten- 2'929800 3/1960 H111 260-775 AP sion. The average increase in modulus between 50 and OTHER REFERENCES 200 percent extension for the product from the polyglycol Saunders et a1 polyurethanes, Pan IL Interscience, of 2000 molecular weight 18 1.19x10- g./d./1 percent 70 New York, 1964, pp. 667 and increase 1n extension.

This example also demonstrates the improved physical MAURICE L WELSH, Primary Examiner properties of a fiber of this invention.

I claim Us. 01. xx.

1. In a process for preparing a segmented linear poly- 75 260 77.5 AP, 775 AT urethane polymer which consists of preparing a prepoly- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTWN Patent No. 5, h l2 Dated April 16', 1974 inventofls) ANTHONY KOROSCIL It is certified that error appears in the above-identified patent: and that said Letters Patent are hereby corrected as shown below:

Column +3, line 14, "immersion" should read immersed Colunm 4, line 52 ochez'" should read eisher Column lines 50 60 the marginal numbers are upside down.

Signed and sealed this 13th day of August 1974.

(SEAL) Attest:

MCCOY M. GIBSON, J'R. C. MARSHALL DANN Attesting Officer Commissioner of Patents F OHM PO-1050 (10-69) UBCOMM-DC 60316-P6B i 0.3. uovllmlllyn "M1016 01mm 1 I98, o-ua-au 

